Monday 16 December 2019

Why leopards really did get their spots

A leopard looks out from a tree at the Mashatu game reserve in Mapungubwe, Botswana. Photo: Getty Images
A leopard looks out from a tree at the Mashatu game reserve in Mapungubwe, Botswana. Photo: Getty Images

Richard Alleyne

Rudyard Kipling was right - leopards really did get their complex spots to hide in the "speckly, patchy-blatchy shadows", scientists claim.

British researchers have proved the author's theory in the Just So stories that unusual pattern provided camouflage in an environment "full of trees and bushes and stripy, speckly, patchy-blatchy shadows".

They have shown that animals live in dense habitats in the trees and active at low light levels are the most likely to be patterned – especially with particularly irregular or complex shapes.

William Allen, a researcher at the University of Bristol, and colleagues investigated the markings of 35 species of wild cats and found their beautiful and intriguing variation is down to evolution.

Mr Allen said: "Rudyard Kipling was wrong by suggesting how leopard got their spots as the fingerprints of a man.

"But he was right about the reason because they provide the perfect camouflage in a forest habitat with dappled light.

"The spotted pattern also allows them to have camouflage in a wider variety of habitats unlike, say, the black leopards who stand out in any environment other than dense rainforest and darkness."

The study, published in Proceedings of the Royal Society B, set out to explain why different cats have completely different markings even though they are closely related.

It suggests the patterning evolved over a short period of time in evolutionary terms and that each coat is tailored to the specific environment.

The research also explains why, for example, black leopard are common but black cheetahs unknown.

Unlike cheetahs, leopards live in a wide range of habitats and have varied behavioural patterns.

His team linked the markings to patterns generated to a mathematical model that showed how each is perfect for their habitat.

The leopard's spots, which are actually rosette shaped, are so cleverly designed that they provide camouflage even when the cat is moving.

Mr Allen said: "The method we have developed offers insights into cat patterning at many levels of explanation and we are now applying it to other groups of animals."

Although a clear link between environment and patterning was established, the study also highlighted some anomalies.

For example, cheetahs have evolved or retained spotted patterns despite a strong preference for open habitats.

But a number of cats, such as the bay cat and the flat-headed cat, have plain coats despite a preference for closed environments.

The study also highlighted just how few species of cats have vertical stripes.

Of the species examined only tigers always had vertically elongated patterns that were not associated with a grassland habitat, as might be expected.

But tigers seem to be very well camouflaged so this raises the question why vertical stripes are not more common in cats and other mammals.

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